Field of the Invention
The present invention relates to a laser beam profiler unit for measuring the profile of a laser beam that has been focused which is to be applied to a workpiece, and a laser processing apparatus incorporating such a laser beam profiler unit.
Description of the Related Art
Generally, there are known laser processing apparatus for applying a laser beam to a workpiece with various devices formed thereon, such as a semiconductor device wafer, to form laser-processed grooves or modified layers in the workpiece along projected dicing lines thereon. In the known laser processing apparatus, the laser beam that is used in various processing applications has its various characteristics including a spot diameter, a spot shape such as a circular shape, an elliptical shape, or the like, and a power density adjusted to optimum conditions depending on the workpiece.
Optical elements that are used in laser oscillators and optical systems tend to have their characteristics shifted gradually from adjusted optimum conditions due to aging-induced deteriorations. For this reason, there have heretofore been proposed technologies for measuring characteristics, known as profile, including a spot shape, an intensity distribution, and so on of a laser beam (see, for example, Japanese Patent Laid-open No. 2010-249727 and Japanese Patent Laid-open No. 2016-41437).